Matthew 7:1, "Judge not, that ye be not judged."
There are many examples of people judging others in the scriptures. Paul prayed that our love would abound more and more in all judgment (Philippians 1:9). In light of the scriptures where Jesus and the disciples spoke of judging, it is evident that there must be a right and a wrong type of judging.
In Luke 12:56-57, Jesus uses the words "discern" and "judge" interchangeably. A dictionary definition of "judge" can mean many things from "condemn" to "appraise, to form an opinion about; to think or consider." There is certainly nothing wrong with discerning or appraising a situation or person. Quite the contrary, we need to try the spirits (1 John 4:1). Judging when done as discernment, is good.
It is the condemning type of judgment that is wrong. We can defer passing sentence on people to God, and know that He will make a perfect judgment (Romans 2:2, Revelation 20:13). God is ultimately the only qualified judge.
Jesus is not forbidding judgment, but rather He is warning to be careful with our judgment because we will be judged accordingly. There are certain cases where we have to pass a condemning sentence as Paul did or as a judge would do today. Pastors and elders are charged with rebuking and even disciplining church members, but it is not something to be done lightly. Judging is not aimed at the person, but the actions of that person. This warning constrains us to be certain that we have heard from God. We must not simply vent our own frustrations.
Every Christian has a need for wisdom in making judgments about how to live from day to day. How wonderful to know that God through His Word has already equipped us to judge.